Numerical Study on Detailed Structure of Vortex Breakdown Behaviour for Landing of Spaceplane

Abstract

To understand the fundamental features of the vortex breakdown phenomena, which may significantly affect the aerodynamic characteristics of a spaceplane having a delta wing flying at high-angles of attack in a low-speed regime, the numerical analyses have been conducted by solving the incompressible Navier-Stokes equations. For simplicity of analysis, the axisymmetric flow around the vortex axis was assumed. To clarify the complicated flowfield structure of the vortex breakdown, the mathematical theory of the dynamical system has been applied to the analysis of the three-dimensional vector field of the flow velocity. The presence of the fixed points and their topological types are successfully identified by analyzing the eigensystem of the local velocity gradient tensor numerically. The topological properties of the streamlines are also clarified by considering the variation of the two-dimensional crossflow pattern with respect to the location on the vortex axis. The appearance of the limit cycle on the crossflow plane has been mathematically explained in relation to the onset of the vortex breakdown.